Both Bale and Leo earned Oscars for their supporting roles in "The Fighter" last year.
Firth and Portman took home Academy Awards for their lead performances in "The King's Speech" and "Black Swan," respectively, at the 83rd edition of the prize presentation.
Previously announced Oscar presenters include Halle Berry, Rose Byrne, Bradley Cooper, Tom Cruise, Penelope Cruz, Cameron Diaz, Michael Douglas, Will Ferrell, Tina Fey, Zach Galifianakis, Tom Hanks, Angelina Jolie, Milla Jovovich, Ellie Kemper, Jennifer Lopez, Melissa McCarthy, Wendi McLendon-Covey, Maya Rudolph, Emma Stone, Meryl Streep and Kristen Wiig.
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